Women diagnosed with ovarian cancer often receive therapy over extended periods of time with multiple treatment regimens. Both the acute and chronic effects of the disease and its treatment are associated with significant side-effects that can adversely impact QoL . And while it is expected that QoL of patients will influence survival, identifying the most important factors in ovarian cancer given its heterogeneity with respect to biology, natural history, and multidisciplinary management is a daunting challenge. In fact, it might be expected that it would be easier to uncover QoL elements associated with survival by investigating parameters that are affected, positively or negatively, as a result of therapy. Therefore, the goal of this study was to evaluate the association between changes in QoL during treatment and overall survival in patients with either newly diagnosed or newly-relapsed ovarian cancer.
We found that significant changes in appetite and constipation symptoms, and in global QoL status within 3 months of beginning treatment were predictive of survival time. This is distinct from previous studies wherein association between baseline QoL and survival was explored in ovarian cancer [12–14]. In the study by Carey et al. in advanced ovarian cancer, baseline global QoL EORTC QLQ-C30 score was found to be an independent predictor for both progression-free and overall survival. Baseline EORTC QLQ-C30 cognitive functioning score was also an additional independent predictor for overall survival. In addition, at 3 months after completion of chemotherapy, global QoL score, performance status and grade were significant independent predictors of overall survival . In a previous study conducted by our research team, baseline QoL was evaluated using Ferrans and Powers Quality of Life Index in 90 ovarian cancer patients. The health and physical domain was found to be significantly (although marginally) associated with survival . Finally, in a recently published study by von Gruenigen et al., conducted in 399 stage III ovarian cancer patients receiving adjuvant chemotherapy, QoL was assessed using the Functional Assessment of Cancer Therapy-General. Poor physical well-being reported at baseline was found to be associated with a significantly increased risk of death . The present study builds on this previous research to explore whether the dynamic effects of therapy on QoL scores (as opposed to a single baseline assessment) is associated with survival in ovarian cancer patients.
The results of this study suggest that baseline QoL should be considered when planning treatment and regular QoL assessment performed during the course of treatment in women with ovarian cancer. Moreover, particular attention should be paid to QoL parameters related to global health, appetite and constipation and, when indicated, suitable interventions to support these parameters should be applied. Positive effects on survival as a consequence of such interventions would go a long way towards establishing causative relationships between these specific QoL parameters and disease control.
Unfortunately, while there has been some progress with respect to the treatment of appetite loss in cancer patients, clinical effectiveness is inconsistent and unpredictable. And there are at present no effective means to address more complex QoL factors such as global health. This challenges the cancer research enterprise to develop greater understanding of the complex physiology responsible for all aspects of QoL, and to use this information to develop more effective and predictable methods to favorably modulate this critical aspect of patient health and wellness.
Several limitations of this study need to be acknowledged. Our study, because of its retrospective nature, relies on data not collected to test a specific hypothesis. As a result, we could not control for certain factors in our analyses that could influence survival such as treatment received, medical co-morbidities, socioeconomic factors, support system, exercise and educational level. The patient cohort was limited only to those patients who were English speakers and therefore is not representative of the complete spectrum of ovarian cancer patients. A majority of our patients had advanced stage disease at presentation and had failed primary treatment elsewhere before coming to our hospital. As a result, we acknowledge that our findings may not be applicable to newly-diagnosed ovarian cancer patients with limited stage disease, an issue that needs to be tested in suitable patient populations.
Moreover, this study does not reveal a causative relationship between QoL and survival. Rather, patient QoL was found to act as a surrogate for otherwise undetected prognostic factors . QoL scores were assessed over a 3-month interval only which may not be sufficient time for score changes to develop in other QoL parameters that may be prognostic of survival. We did not control for the multiple comparisons made in this study, but this is acceptable for hypothesis-generating studies .
This study also has several strengths, including no missing data on any EORTC QLQ-C30 variables for the entire study sample; the use of a valid and reliable QoL instrument; the availability of clinical parameters in nearly all patients; and availability of mature and reliable survival data. As is the case for all exploratory retrospective studies, the most important outcome that can be achieved is the development of a hypothesis suggested by the results. As a consequence of this study, we hypothesize that the parameters of appetite loss, constipation and global health are independent determinants of survival in ovarian cancer, and should be regularly assessed and when indicated, targeted for intervention.